Smarbar,
Thanks for your response, it's appreciated.  Unfortunately, this didn't work.   I ran through the Add/remove and then a "change", but when the Mitel client then launched, it didn't run through the wizard again.  If I run the wizard manually off of the Mitel button, it skips right over step 3 which is the one that allows you to click Exchange Calendar Integration.
I've also tried deleting the c:\Users\<username>\AppData\Roaming\Mitel.   This allows the wizard to run again after launching UCA, but again, it skips step 3.  I've searched for a registry entry with no luck as well.  There has to be a setting somewhere on my PC that can be changed to get this back. 
Anyone else?
-Bryan